PhD theses from Geography and Earth Scienceshttp://hdl.handle.net/2160/671
Tue, 03 Mar 2015 20:27:49 GMT2015-03-03T20:27:49ZDistribution and character of mid-latitude glacier-like forms on Marshttp://hdl.handle.net/2160/13201
Distribution and character of mid-latitude glacier-like forms on Mars
Souness, Colin James
Abstract
Mars‟ mid-latitudes host a range of apparently flow-related landforms that strongly
resemble terrestrial glaciers. Such „glacier-like forms‟ (GLFs) are strikingly similar to
alpine valley glaciers found on Earth. These martian GLFs are believed to be
composed of massive water ice but little is known about how they formed, how they
evolve, and how they interact with the martian surface. This thesis presents various
studies of Mars‟ mid-latitude GLFs that were designed to address some of these
issues. New observations and new results were obtained using survey and mapping
techniques.
The findings presented in this thesis suggest that GLFs, observed ubiquitously in
Mars‟ mid-latitudes, are all composed of a similar material and were formed in a
similar way, most likely under Earth-like „mass-balance‟ conditions whereby ice
accumulated at altitude and subsequently flowed, under its own weight, downhill and
into an ablation zone where GLFs experienced net mass loss. It is likely these
conditions existed on Mars during a past martian ice age.
From their geographical distribution (relative to latitude, elevation and relief) it would
appear that those GLFs that remain on Mars today are relict deposits that have
survived where local conditions impair ablation, and that these residual GLFs appear
currently to flow under the influence of local relief and gravity. From the examination
of crevasse patterns it appears that this flow occurs under an englacial strain regime
similar to that which commonly defines spatial flow patterns in terrestrial glaciers.
This thesis also observes and identifies various small-scale features and textures
that suggest that the evolution and subsequent flow of GLFs has been (or may
currently be) sensitive to many environmental factors common on Earth, such as the
agency of liquid water. This suggests that GLFs (and possibly other associated ice
masses) may have been significant movers and shapers of Mars‟ surface sediments
and structures, contributing widely to the evolution of Mars‟ present-day surface.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/2160/132012013-01-01T00:00:00ZHydrological politics in megacity: rethinking water governance in Delhihttp://hdl.handle.net/2160/12136
Hydrological politics in megacity: rethinking water governance in Delhi
Kumar, Chandra Bhushan
Thesis Summary
This thesis is about the juxtaposition of two dominant themes of today’s world – megaurbanization and water management. It sets out to investigate the contemporary water management conditions in a South megacity. In this investigation, the hydraulics serve two purposes: one, as a frame to apprehend various processes that created (and are creating) myriad relationships in this gigantic urban space; and two, as an object of inquiry reveals the genealogy of the ideas or institutions that has led to the spatiotemporal arrangements of the domestic water supply in the megacity.
Drawing insights from various analytical perspectives including hydrosocial, urban political ecology, subaltern urbanism, governmentality, postcolonialism, and modernity, the thesis surveys the process of mega-urbanization that shaped the form and design of institutional frameworks, laden with singular and modernist vision of water, and holds this vision and its apparatus – state monopoly and segregation- as key producers of multi-layered and diverse risks in water management for the households, the megacity, and the region. Using results from extensive fieldwork in Delhi, the thesis proposes an alternative view to analyse the contemporary concerns and to suggest possible pathways in megacity water management.
Rapid emergence of megacities in global South and related concerns of water supply in these places have been investigated, to a large extent, from binary perspectives of planned/slum; formal/informal; economic good/social good; and efficiency/equity. Taking Linton’s (2010) phrase ‘from waters to water’ as a starting point, the thesis travels back into history to witness the hesitant and incomplete transformation of ‘multiple waters’ into ‘singular and modernist water’ in the megacity. It helps first in dismantling the myth of binary understanding of the megacity; second, in unearthing the fundamental barriers embedded in the contemporary technoinstitutional regime of the megacity hydraulics; third, in reconstructing the cultural landscapes of water in the megacity, which are gradually marginalized and lost in the dominant discourse on demand and supply of water; and fourth, in indicating the presence of spatio-temporality of risks of different orders in the megacity.
Next, using empirical results from more than five thousand households in 32 locations within Delhi, the thesis demonstrates the presence of first order risks concerning accessibility, adequacy, quality, affordability, acceptability, seasonal, and source depletion. The management of these risks and the methods of this management, the thesis argues, produce second order risks which are mostly invisible, distant in time and space, uncertain, and politically unattractive. Putting household in focus, the thesis follows a familiar trajectory of measurement of coping strategy; but then it indicates departure by making household as a crucible of ideology and risk management strategies in water management. This innovative approach helps in reconstructing the ideological premise and its workable instruments for the megacity water management, that are as diverse, flexible, dynamic, inclusive, and holistic as a megacity.
From knowledge perspective, the thesis contributes the following: first, the binary understanding of a south megacity is a myth and needs to be dismantled as it promotes a singular and modernist vision of water ignoring the local geo-cultural conditions and practices; second, the contemporary megacity water management faces different orders of risks, and its focus on first order risks often remains (or choose to) ignorant of second order risks; third, the household is not only a place to assess the risks and to advance the arguments of willingness to pay, but it is also a significant functional institution to offer ideas and workable solutions, which are local, indigenous, just, and sustainable.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/2160/121362012-01-01T00:00:00ZAn assessment of the stability of southwest Antarctic Peninsula Ice Shelveshttp://hdl.handle.net/2160/12130
An assessment of the stability of southwest Antarctic Peninsula Ice Shelves
Holt, Thomas Owen
Abstract
Over the last three decades, Antarctic Peninsula Ice Shelves have shown a pattern of sustained retreat, often ending in catastrophic and rapid breakup. This study provides a detailed analysis of the structures and dynamics of Bach, George VI and Stange Ice Shelves, situated on the southwest Antarctic Peninsula, to determine their current and future stability on the premise that glaciological changes can be identified well in advance of final breakup phases. Spatial extent and glaciological surface features were mapped for each ice shelf from 1973 to 2010 using optical and radar satellite images to assess their structural stability, structural evolution and historical dynamics. A combination of InSAR and feature tracking methods has been used to assess the recent dynamic configurations of the ice shelves from 1989 to 2010, with repeat ICESat measurements used to evaluate their vertical changes from 2003 to 2008. On Bach Ice Shelf, the formation of two large fractures near the ice front is linked to widespread thinning (~2 ma-1) and sustained retreat (~360 km2). It is postulated that iceberg calving along these fractures will alter the frontal geometry sufficiently to promote enhanced, irreversible retreat within the next decade. On George VI Ice Shelf, acceleration is observed at both ice fronts linked to a release of back-stresses through continued ice loss (1995 km2 in total). The most significant changes are recorded at its southern ice front, with ice flow accelerating up to 360% between ca. 1989 and ca. 2010, coupled with widespread rifting and a mean thinning rate of 2.1 ma-1. On Stange Ice Shelf, shear-induced fracturing was observed between two flow units, also linked to widespread thinning (~4.2 ma-1) illustrating a response of southwest Antarctic Peninsula Ice Shelves within the proposed limit of viability. A semi-quantitative assessment reveals that the southern margin of George VI Ice Shelf is most susceptible to rapid retreat, whilst its northern ice front, Bach Ice Shelf and the northern front of Stange Ice Shelf are more vulnerable than those situated on the east Antarctic Peninsula.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/2160/121302013-01-01T00:00:00ZHuman-environment interactions during periods of extreme weather in southwest Wales, 1846-1947http://hdl.handle.net/2160/12094
Human-environment interactions during periods of extreme weather in southwest Wales, 1846-1947
Jones, Cerys Ann
Summary
Climate change projections include increasing intensity and frequency in periods of
extreme weather. Investigating individual experiences of past episodes through archivebased research and oral histories can provide valuable insights to the nature of humanenvironment interactions during periods of extreme weather. Analysis of three case studies of varying meteorological, temporal and geographical characteristics, namely the 1846 flooding, the 1887–88 drought and 1946/47 winter on a local scale of southwest Wales from a qualitative perspective enables the detection of details which would not otherwise have been recognised in global and/or statistical equivalents, especially as acute meteorological extremes that straddle temporal boundaries are unlikely to be detected within compilations of instrumental data. This research highlights how individuals and communities document, are impacted, respond and mitigate against periods of extreme weather. Individual and community vulnerability to extreme weather is found to be affected by factors of amplification and resilience, namely: i) dependency on agriculture, because of its temporalities of recovery and is highly meteorologically-influenced by rain, drought and snow; ii) geographical extent of the extreme weather, as it can affect the level of aid received from remote beneficiaries; iii) technological advancements, which can help before, during and after the extreme weather by forecasting and facilitating effective responses; iv) class and economic standing, as the poor are disproportionately impacted by extreme weather; and, v) memory, through the meteorological and wider temporal context.
In the light of current climate predictions, individual and/or community scale studies
should form a key focus of research in addition to those which focus on policy or national responses.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/2160/120942013-01-01T00:00:00Z